Star Formation Efficiencies at Giant Molecular Cloud Scales in the Molecular Disk of the Elliptical Galaxy NGC 5128 (Centaurus A)
Journal article, 2019

We present ALMA CO (1-0) observations toward the dust lane of the nearest elliptical and radio galaxy, NGC 5128 (Centaurus A), with high angular resolution (similar to 1 '', or 18 pc), including information from large to small spatial scales and total flux. We find a total molecular gas mass of 1.6 x 10(9) M-circle dot and reveal the presence of filamentary components more extended than previously seen, up to a radius of 4 kpc. We find that the global star formation rate is similar to 1 M-circle dot yr(-1), which yields a star formation efficiency (SFE) of 0.6 Gyr(-1) (depletion time tau = 1.5 Gyr), similar to those in disk galaxies. We show the most detailed view to date (40 pc resolution) of the relation between molecular gas and star formation within the stellar component of an elliptical galaxy, from a scale of several kiloparsecs to the circumnuclear region close to the powerful radio jet. Although on average the SFEs are similar to those of spiral galaxies, the circumnuclear disk (CND) presents SFEs of 0.3 Gyr(-1), lower by a factor of 4 than the outer disk. The low SFE in the CND is in contrast to the high SFEs found in the literature for the circumnuclear regions of some nearby disk galaxies with nuclear activity, probably as a result of larger shear motions and longer active galactic nucleus feedback. The higher SFEs in the outer disk suggest that only central molecular gas or filaments with sufficient density and strong shear motions will remain in similar to 1 Gyr, which will later result in the compact molecular distributions and low SFEs usually seen in other giant ellipticals with cold gas.

galaxies: star formation

ISM: molecules

galaxies: individual (NGC 5128)

galaxies: nuclei

galaxies: elliptical and lenticular, cD


D. Espada

The Graduate University for Advanced Studies (SOKENDAI)

National Astronomical Observatory of Japan

S. Verley

Universidad de Granada

R. E. Miura

National Astronomical Observatory of Japan

F. P. Israel

Leiden University

C. Henkel

King Abdulaziz University

Max Planck Society

S. Matsushita

Academia Sinica

B. Vila-Vilaro

European Southern Observatory Santiago

Atacama Large Millimeter-submillimeter Array (ALMA)

J. Ott

National Radio Astronomy Observatory Socorro

K. Morokuma-Matsui

Japan Aerospace Exploration Agency

University of Tokyo

A. B. Peck

Gemini Observatory North

A. Hirota

Atacama Large Millimeter-submillimeter Array (ALMA)

National Astronomical Observatory of Japan

Susanne Aalto

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

A. C. Quillen

University of Rochester

M. R. Hogerheijde

University of Amsterdam

Leiden University

N. Neumayer

Max Planck Society

C. Vlahakis

National Radio Astronomy Observatory

D. Iono

The Graduate University for Advanced Studies (SOKENDAI)

National Astronomical Observatory of Japan

K. Kohno

University of Tokyo

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 887 1 88

Subject Categories

Astronomy, Astrophysics and Cosmology

Other Earth and Related Environmental Sciences

Geosciences, Multidisciplinary


Onsala Space Observatory



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